In this paper, four different localization techniques based on TDOA-measurements for single sensor passive emitter localization are proposed. The use of signal structure information allows TDOA-based localization with a single moving sensor node. A direct position estimation scheme is derived for the single sensor TDOA localization problem. The feasibility of the proposed method is shown in simulations. The position estimation accuracy of the single sensor TDOA and the direct technique are compared using simulation results and the Cramer´-Rao Lower Bound. Field experiments using an airborne sensor are conducted to prove the concept.